Light-emitting diode (LED) is of much importance in solid-state devices with a characteristic of photo-electronic conversion. Generally speaking, LED has an active layer sandwiched by two semiconductor layers with different conductivity types. When driving current is applied to electrodes above the two semiconductor layers, electrons and holes of the two semiconductor layers inject into and combine with each other in the active layer to emit light. The light is omni-directional, so it emits out from the active layer to each surface of the LED.
Meanwhile, LED is also widely used as a light source. Comparing with traditional incandescent lamp or fluorescent lamp, LED has outstanding features like efficient energy and long lifetime. Therefore, LED gradually takes the place of the traditional light sources and be widely used in a variety of fields such as traffic signals, backlight module, street lamp lighting and medical treatment devices. As the LED light sources develop and have more applications, the demand of luminance is growing higher. Hence, how to increase the light efficiency of LEDs to improve luminous thereof is an important direction for the industry to strive for.
The field worthy of studying is how to increase light efficiency by a design of sealing structure. At present a cup-like structure is generally adopted, and LED is disposed at a center of the cup to control the light distribution by taking advantage of the shapes of the cup and sealing materials. In addition, sealing materials, the reflection ability of the carrier, the shape of the cup and so on can also affect light efficiency.
In view of the foregoing, there is a need of a photoelectronic device that provides the improvement of light efficiency.